A Combinatorial Approach to Reliable Quantitative Analysis of Small Nano-Sized Precipitates: A Case Study with α′ Precipitates in Fe–20 at% Cr Alloy

2021 ◽  
pp. 1-15
Author(s):  
Sudip Kumar Sarkar ◽  
Deodatta Shinde ◽  
Debasis Sen ◽  
Aniruddha Biswas
Keyword(s):  
Quantitative Analysis ◽  
Chemical Composition ◽  
Volume Fraction ◽  
Atom Probe ◽  
Combinatorial Approach ◽  
Transmission Electron ◽  
True Representation ◽  
Complementary Techniques ◽  
The Individual

The quantitative characterization of small nano-sized precipitates poses genuine challenges and is often deficient in accuracy due to the inherent limitations inevitably associated with the individual experimental techniques. A convenient solution is to utilize multiple complementary techniques. The present work demonstrates an effective way to reliably quantify nano-sized precipitates using a combination of complementary techniques of atom probe tomography (APT), small angle neutron scattering (SANS), and transmission electron microscopy (TEM). As a case study, the size (radius, r), number density (NP), volume fraction (ϕ), and chemical composition of Cr-rich α′ precipitates are determined in Fe–20 at% Cr alloy, thermally aged at 773 K for 1,000 h. This combinatorial approach utilizes the strength of each technique in such a way that the overall accuracy of quantitative precipitation analysis improves significantly. For example, the superior spatial resolution makes TEM the appropriate technique to estimate the size and size distribution of the precipitates, while APT provides the chemical composition. Similarly, SANS analysis incorporates both the size and the compositional information thus derived independently and provides statiscally averaged quantitative analysis overcoming the field-of-view limitations of both TEM and APT. This combinatorial approach improves the accuracy of quantification and provides the true representation of the microstructure.

Precipitation Sequence and Kinetics in an Fe-Si-Ti Alloy

2011 ◽  
Vol 172-174 ◽  
pp. 833-838 ◽  
Author(s):  
Malika Perrier ◽  
Alexis Deschamps ◽  
Patricia Donnadieu ◽  
Frédéric de Geuser ◽  
Frédéric Danoix ◽  
...  
Keyword(s):  
Volume Fraction ◽  
High Volume ◽  
Tensile Tests ◽  
Atom Probe ◽  
Precipitate Size ◽  
Precipitation Sequence ◽  
Precipitation Kinetics ◽  
Temperature Range ◽  
Transmission Electron ◽  
Temporary Decrease

The Fe-Si-Ti system is known to show nanoscale precipitation of the Fe2SiTi Heusler phase with potentially high volume fraction (~4%), very high density and a size ranging from 1 to 20nm after artificial aging. The strong hardening potential of these precipitates make these steels candidates for automotive applications; however no understanding of the precipitation sequence (competition with other phases) nor the precipitation kinetics are available. The present study presents a quantitative study of the precipitation kinetics (size, volume fraction and number density) in a wide temperature range (450-800°C), realised by coupling systematically Small Angle Neutron Scattering (SANS), Transmission Electron microscopy (TEM) and Tomographic Atom Probe (TAP). Tensile tests were also carried out so as to determine the microstructure/properties relationships. Along the complete temperature range, it is shown that a compromise between time for precipitation and small precipitate sizes can be reached around 550°C. At this intermediate temperature, precipitation is shown to occur in two steps, linked with a second nucleation process after nucleation & growth of the first family of Fe2SiTi has been completed. This second precipitation step results in a temporary decrease in precipitate size and an increase in hardness. The nature of these precipitates is discussed in view of the TEM and TAP observations.

Thermal Stability of Severe Plastically Deformed VT-6 (Ti-6Al-4V)

2008 ◽  
Vol 584-586 ◽  
pp. 893-898 ◽  
Author(s):  
Henry J. Rack ◽  
Javaid Qazi ◽  
L. Allard ◽  
Ruslan Valiev
Keyword(s):  
Thermal Stability ◽  
Volume Fraction ◽  
Tem Analysis ◽  
Β Phase ◽  
Transmission Electron ◽  
Continuous Recrystallization ◽  
Hardness Increase ◽  
Lower Temperature ◽  
The Individual ◽  
Thermal Stability Of

The thermal stability of equal channel angular extruded VT-6(Ti-6Al-4V) has been examined using micro-hardness, nano-hardness of the individual αand β phases backscattered scanning (BSEI) and transmission electron microscopy (TEM). After straining to an equivalent total equivalent of 6.5 samples were annealed for 1 h at temperatures between 175 and 800 o C followed by water quenching. Micro and nano-hardness measurements showed an initial hardness increase, the former rising to a maximum at 175°C, while the latter exhibited a maximum at 500°C. BSEI and TEM analysis showed that these observations can be understood by considering the microstructure changes occurring at different length scales. Annealing in the temperature range of 175 to 500°C did not significantly alter the α and β particle size, while TEM showed that recovery and continuous recrystallization occurred in the α phase, higher temperatures being required to activate the recovery and recrystallization processes within the β phase. Finally at temperatures above 600°C spheroidization and growth of the β phase occurred with the volume fraction of this phase increasing from 15 pct at lower temperature to 25 pct at 800°C, an equi-axed α+ β microstructure being observed at this temperature.

scholarly journals Infrared photo-induced force microscopy unveils nanoscale features of Norway spruce fibre wall

Cellulose ◽  
2021 ◽  
Author(s):  
Kavindra Kumar Kesari ◽  
Padraic O’Reilly ◽  
Jani Seitsonen ◽  
Janne Ruokolainen ◽  
Tapani Vuorinen
Keyword(s):  
Cell Wall ◽  
Chemical Composition ◽  
Norway Spruce ◽  
Spatial Resolution ◽  
Lignin Content ◽  
Force Microscopy ◽  
Transmission Electron ◽  
High Resolution Images ◽  
The Individual ◽  
20 Nm

AbstractInfrared photo-induced force microscopy (IR PiFM) was applied for imaging ultrathin sections of Norway spruce (Picea abies) at 800–1885 cm−1 with varying scanning steps from 0.6 to 30 nm. Cell wall sublayers were visualized in the low-resolution mode based on differences in their chemical composition. The spectra from the individual sublayers demonstrated differences in the orientation of cellulose elementary fibrils (EFs) and in the content and structure of lignin. The high-resolution images revealed 5–20 nm wide lignin-free areas in the S1 layer. Full spectra collected from a non-lignified spot and at a short distance apart from it verified an abrupt change in the lignin content and the presence of tangentially oriented EFs. Line scans across the lignin-free areas corresponded to a spatial resolution of ≤ 5 nm. The ability of IR PiFM to resolve structures based on their chemical composition differentiates it from transmission electron microscopy that can reach a similar spatial resolution in imaging ultrathin wood sections. In comparison with Raman imaging, IR PiFM can acquire chemical images with ≥ 50 times higher spatial resolution. IR PiFM is also a surface-sensitive technique that is important for reaching the high spatial resolution in anisotropic samples like the cell wall. All these features make IR PiFM a highly promising technique for analyzing the recalcitrant nature of lignocellulosic biomass for its conversion into various materials and chemicals. Graphic abstract

scholarly journals Estimation of aerosol water and chemical composition from AERONET Sun–sky radiometer measurements at Cabauw, the Netherlands

2014 ◽  
Vol 14 (12) ◽  
pp. 5969-5987 ◽  
Author(s):  
A. J. van Beelen ◽  
G. J. H. Roelofs ◽  
O. P. Hasekamp ◽  
J. S. Henzing ◽  
T. Röckmann
Keyword(s):  
Refractive Index ◽  
Organic Matter ◽  
Chemical Composition ◽  
Relative Humidity ◽  
Volume Fraction ◽  
Inorganic Salts ◽  
Water Volume ◽  
Aerosol Composition ◽  
Water Volume Fraction ◽  
The Individual

Abstract. Remote sensing of aerosols provides important information on atmospheric aerosol abundance. However, due to the hygroscopic nature of aerosol particles observed aerosol optical properties are influenced by atmospheric humidity, and the measurements do not unambiguously characterize the aerosol dry mass and composition, which complicates the comparison with aerosol models. In this study we derive aerosol water and chemical composition by a modeling approach that combines individual measurements of remotely sensed aerosol properties (e.g., optical thickness, single-scattering albedo, refractive index and size distribution) from an AERONET (Aerosol Robotic Network) Sun–sky radiometer with radiosonde measurements of relative humidity. The model simulates water uptake by aerosols based on the chemical composition (e.g., sulfates, ammonium, nitrate, organic matter and black carbon) and size distribution. A minimization method is used to calculate aerosol composition and concentration, which are then compared to in situ measurements from the Intensive Measurement Campaign At the Cabauw Tower (IMPACT, May 2008, the Netherlands). Computed concentrations show good agreement with campaign-average (i.e., 1–14 May) surface observations (mean bias is 3% for PM10 and 4–25% for the individual compounds). They follow the day-to-day (synoptic) variability in the observations and are in reasonable agreement for daily average concentrations (i.e., mean bias is 5% for PM10 and black carbon, 10% for the inorganic salts and 18% for organic matter; root-mean-squared deviations are 26% for PM10 and 35–45% for the individual compounds). The modeled water volume fraction is highly variable and strongly dependent on composition. During this campaign we find that it is >0.5 at approximately 80% relative humidity (RH) when the aerosol composition is dominated by hygroscopic inorganic salts, and <0.1 when RH is below 40%, especially when the composition is dominated by less hygroscopic compounds such as organic matter. The scattering enhancement factor (f(RH), the ratio of the scattering coefficient at 85% RH and its dry value at 676 nm) during 1–14 May is 2.6 ± 0.5. The uncertainty in AERONET (real) refractive index (0.025–0.05) is the largest source of uncertainty in the modeled aerosol composition and leads to an uncertainty of 0.1–0.25 (50–100%) in aerosol water volume fraction. Our methodology performs relatively well at Cabauw, but a better performance may be expected for regions with higher aerosol loading where the uncertainties in the AERONET inversions are smaller.

scholarly journals Chemical composition and mixing-state of ice residuals sampled within mixed phase clouds

2010 ◽  
Vol 10 (10) ◽  
pp. 23865-23894 ◽  
Author(s):  
M. Ebert ◽  
A. Worringen ◽  
N. Benker ◽  
S. Mertes ◽  
E. Weingartner ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Mixed Phase ◽  
Research Station ◽  
Mixing State ◽  
Transmission Electron ◽  
Anthropogenic Component ◽  
Significant Enrichment ◽  
Alpine Research ◽  
The Individual ◽  
Mixed Phase Clouds

Abstract. During an intensive campaign at the high alpine research station Jungfraujoch, Switzerland, in February/March 2006 ice particle residuals within mixed-phase clouds were sampled using the Ice-counterflow virtual impactor (Ice-CVI). Size, morphology, chemical composition, mineralogy and mixing state of the ice residual and the interstitial (i.e., non-activated) aerosol particles were analyzed by scanning and transmission electron microscopy. Ice nuclei (IN) were identified from the significant enrichment of particle groups in the ice residual (IR) samples relative to the interstitial aerosol. In terms of number lead-bearing particles are enriched by a factor of approximately 25, complex internal mixtures with silicates or metal oxides as major components by a factor of 11, and mixtures of secondary aerosol and soot (C-O-S particles) by a factor of 2. Other particle groups (sulfates, sea salt, Ca-rich particles, external silicates) observed in the ice-residual samples cannot be assigned unambiguously as IN. Between 9 and 24% of all IR are Pb-bearing particles. Pb was found as major component in around 10% of these particles (PbO, PbCl2). In the other particles, Pb was found as some 100 nm sized agglomerates consisting of 3–8 nm sized primary particles (PbS, elemental Pb). C-O-S particles are present in the IR at an abundance of 17–27%. The soot component within these particles is strongly aged. Complex internal mixtures occur in the IR at an abundance of 9–15%. Most IN identified at the Jungfraujoch station are internal mixtures containing anthropogenic components (either as main or minor constituent), and it is concluded that admixture of the anthropogenic component is responsible for the increased IN efficiency within mixed phase clouds. The mixing state appears to be a key parameter for the ice nucleation behaviour that cannot be predicted from the separate components contained within the individual particles.

Stress–strain behaviors of Ti-based bulk metallic glass and their nanostructures

2007 ◽  
Vol 22 (5) ◽  
pp. 1406-1413 ◽  
Author(s):  
T. Ohkubo ◽  
D. Nagahama ◽  
T. Mukai ◽  
K. Hono
Keyword(s):  
Plastic Strain ◽  
Metallic Glasses ◽  
Volume Fraction ◽  
Bulk Metallic Glasses ◽  
Three Dimensional ◽  
Atom Probe ◽  
Stress Strain ◽  
Annealing Conditions ◽  
Transmission Electron ◽  
Mold Casting

We have investigated the compression stress–strain behaviors of Ti40Zr25Cu12Ni3Be20 bulk metallic glasses prepared by Cu mold casting from various melt temperatures. Plastic strain was found to vary sensitively on the temperature of melts and subsequent annealing conditions. To understand the origin of the plasticity change, the microstructures were characterized using transmission electron microscopy and a laser-assisted three-dimensional atom probe. The fully amorphous sample cast from 1273 K showed 0.6% plastic strain, and it was enhanced to 1.3% after isothermal annealing at 573 K. The sample cast from 1423 K showed 3.0% plastic strain, from which the presence of nanocrystals with a volume fraction of about 12% was confirmed. The sample cast from a higher temperature (1573 K) contained a larger fraction of crystals, which showed limited plastic strain. The effect of the volume fraction of the nanocrystals on the plasticity of bulk metallic glasses is discussed based on the experimental results.

scholarly journals Atom-Probe Tomography – Different Analysis Tools for Three-Dimensional Atomic-Resolution Data

2008 ◽  
Vol 16 (6) ◽  
pp. 10-13
Author(s):  
Robert M. Ulfig ◽  
David J. Larson ◽  
David A. Reinhard ◽  
Thomas F. Kelly
Keyword(s):  
Electron Microscopy ◽  
Atom Probe Tomography ◽  
Three Dimensional ◽  
Atom Probe ◽  
Field Of View ◽  
Microscopy Technique ◽  
Digital Format ◽  
Transmission Electron ◽  
Probe Experiment ◽  
Complementary Techniques

Like no other microscopy technique, atom-probe tomography (APT) requires detailed data analysis algorithms specific to the knowledge desired, as the data are both complex due to their three-dimensional nature and can only be collected in a digital format. With recent increases in speed and field of view available in contemporary instruments like the Imago Scientific Instruments LEAP™ microscopes, these challenges and significant benefits are exacerbated. In practice, ‘data collection’ in APT, as understood in complementary techniques like scanning electron microscopy (SEM) or transmission electron microscopy (TEM), does not even begin until after the atom-probe experiment is over and the microscopist leaves the laboratory. The sample is prepared into the appropriate needle-shaped geometry, field evaporated atom by atom, and the ‘experiment’ part of the specimen analysis is over as soon as the ions are detected and stored in a digital file.

Transformation Kinetics and Resulting Microstructure in MMC Reinforced with TiC Particles

2011 ◽  
Vol 172-174 ◽  
pp. 747-752 ◽  
Author(s):  
Mickael Mourot ◽  
Alice Courleux ◽  
Moukrane Dehmas ◽  
Elisabeth Aeby-Gautier ◽  
Guillaume Geandier ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Chemical Composition ◽  
Chemical Reactivity ◽  
Atom Probe ◽  
Steel Matrix ◽  
Transformation Kinetics ◽  
Consolidation Process ◽  
Phase Transformation Kinetics ◽  
The Matrix ◽  
Complementary Techniques

The phase transformation kinetics on cooling and resulting microstructures of steel-based matrix composites (MMC) reinforced with TiC particles by powder metallurgy were studied. In addition, the phase transformation kinetics of the MMC were compared to those of the same steel without TiC and consolidated in the same conditions. The presence of TiC particles strongly favors the diffusive transformations in the steel matrix of the MMC. Different complementary techniques (XRD, SEM, TEM/EDX, atom probe tomography, in situ synchrotron XRD) were performed to analyze the chemical reactivity between TiC particles and the steel powders occurring during consolidation process and further heat treatments. Composition changes in the TiC as well as in the matrix were characterized. The chemical composition after treatment in the TiC particles tends toward the thermodynamic calculations with ThermoCalc. The effect of changes in chemical composition and the role of TiC particles acting as new favorable nucleation sites are discussed in regards to the obtained results.

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